Indicator Assessment

Marine phenology

Indicator Assessment
Prod-ID: IND-101-en
  Also known as: CLIM 014
Published 08 Sep 2008 Last modified 11 May 2021
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  • Temperature increases in the ocean have caused many marine organisms in European seas to appear earlier in their seasonal cycles than in the past. For example, some species have moved forward in their seasonal cycle by 4-6 weeks.
  • Changes in the timing of seasonal cycles have important consequences for the way organisms within an ecosystem interact and ultimately for the structure of marine food-webs at all trophic levels. The consequences include:
    - increased vulnerability of North Sea cod stocks to over-fishing;
    - decline in seabird populations.
  • Marine species may be able to adapt genetically to changed conditions. However, with the current pace of climate warming this may be hampered because genetic changes require several reproductive cycles to occur.

Update planned for November 2012

Decapod abundance in the central North Sea 1950-2005

Note: Left: year vs

Data source:

Edwards M. and Richardson A. J., 2004. Impact of climate change on marine pelagic phenology and trophic mismatch. Nature 430: 881884. (left and right) Hadley Centre ( (right)

Past trends

In the North Sea, work on pelagic phenology has shown that plankton communities, including fish larvae, are very sensitive to regional climate warming with the response to warming varying between trophic levels and functional groups. However the ability and speed at which fish and planktonic communities adapt to climate warming is not yet known. In other European regional areas, long-term data on marine phenology changes are quite sparse. According to some preliminary studies, there has also been some phenological movement in certain copepod species in the Mediterranean Sea over the past decade (Juan-Carlos Molinero, pers. com.).
Due to the sensitivity of their physiological development to temperature, decapod larvae were selected as representative of phenological changes in shelf-sea environments (Lindley, 1987). The zooplankton growing season indicator shows the annual timing of peak seasonal abundance of decapod larvae from 1958-2005 in the central North Sea (Figure 1 left). A shift towards an earlier seasonal peak is clearly visible. In particular, since 1988, the seasonal development of decapod larvae has occurred much earlier than the long-term average (baseline mean: 1958-2005) - in the 1990s up to 4-5 weeks earlier than the long-term average This trend towards an earlier seasonal appearance of decapod larvae during the 1990s is highly correlated with sea surface temperature (Figure 1 right).


Projections of how individual species react to future climate change have not yet been made, but the empirical evidence suggests that it is very likely that phenological changes will continue to occur as climate warming continues to accelerate. It is currently much less certain to what degree genetic adaptations within species populations can cope with these changes and whether the current pace of climate warming is too fast for genetic adaptations to take place.

Supporting information

Indicator definition

  • Decapod abundance in the central North Sea 1950-2005
  • Change in colour index in southern North Sea from the 1950s until 2000s



Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The aim is to increase the resilience to climate change of health, property and the productive functions of land, inter alia by improving the management of water resources and ecosystems. More knowledge is needed on climate impact and vulnerability but a considerable amount of information and research already exists which can be shared better through a proposed Clearing House Mechanism. The White Paper stresses the need to mainstream adaptation into existing and new EU policies. A number of Member States have already taken action and several have prepared national adaptation plans. The EU is also developing actions to enhance and finance adaptation in developing countries as part of a new post-2012 global climate agreement expected in Copenhagen (Dec. 2009). For more information see:


No targets have been specified

Related policy documents

No related policy documents have been specified



Methodology for indicator calculation

Methodology for gap filling

Methodology references

No methodology references available.



Methodology uncertainty

Data sets uncertainty

Rationale uncertainty

No uncertainty has been specified

Data sources

Other info

DPSIR: Impact
Typology: Descriptive indicator (Type A - What is happening to the environment and to humans?)
Indicator codes
  • CLIM 014
EEA Contact Info


Geographic coverage

Temporal coverage




Filed under:
Filed under: climate change
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